A friend of mine has just bought a car, its a normal 4wd skyline, but converted to run an RB25GTS motor.

Anyone know how much (if at all) the normal "poverty spec" 4wd skylines vary from the GTR ones?

I didnt even know they did any 4wd ones other than the GTR to be honest, so obviously know nothing about the specifics.

Is it the same box, diffs etc, or are there any differences?


Thanks in advance for any help

 

GTS or GTST motor?

GTS4 and GTST4 were non GTRs but had 4wd.

And yes, they had same GTR active torque split 4wd system, just slighter lower geared diffs.

 

Its a GTST

He was told it started life as a normal (non turbo) one and had an engine swap, but that might not really be the case if they did the GTST as 4wd anyway.

He is looking to get more power from the engine, and i said i would be concerned aobut the box if it wasnt a GTR one, but obviously from what you are saying its not an issue with the gearbox and he can happily gas the bollocks out of the engine without worrying about the 4wd system breaking

What are the RB25 internals like, you got any links to details of them?

I know the turbos shit themseleves before they even get to a bar, but how are the pistons for extra power?

 

Only made R32s as GTST4s, 33s and 34s we're non turbo GTS4's.

GTS4 and GTR boxs are all strong enough, as are the diffs.

RB25 internals can take 600bhp with no mods if mapped right.

Turbos are usually ok at a bar.

If its got a MPH convertor that goes between the gearbox drive and engine, throw it away, thats what makes 4wd skylines so tailhappy and not like a 4wd at all, esp R32GTRs (basicly tricks 4wd system and makes it poo, when you doing 100mph it thinks its doing 100mkh, ie 62mph, so the 4wd acts differently, not as much, and then you go backwards into a ditch )
Worn transfer boxes dont help either.

 

Thanks very much for the info Steve, much appreciated

 

What sort of power can the standard GTR gearbox handle ? Do all the GTR's use the same gearbox or are they different ?

James

 

There are 1000bhp GTRs in the world using standard boxes, they just dont do hard standing starts or rush the gear changes.

But with mega hard use people smash standard boxes with 500-550bhp.

R34 boxes are 6speed and not quite as strong as 32/33 5speeders, but not much difference.

Bloke whos doing my engine runs consistant 10.1s on a totally standard R32GTST-4 ?(ie almost same as GTR) transmission, and thats with 7500rpm foot to floor launches on wrinkle wall slicks with a 75bhp shot of gas too.
Breaks em a fair bit, but they last long enough for him to not bother going for an uprated one.

 

thats pretty impressive for a standard box. Are you using one in your R32 ?

 

Yea, using standard R32GTR box for now, it wont last for ever, but IMO it will last long enough to not justify the cost of uprated ones for me, esp as they always breaking.

Could say same about Supra boxes, and EVO boxes, and prob some others

 

I have a Trust (Quaife) 6 spd sequential for sale if your interested Steve.

 

Not got that kind of money at mo mate, sorry.

And frankly im THAT close to fucking the 4wd off and converting it to RWD itd be not needed anyhow

 

What box would you use if you go RWD then mate?

 

Why do you want to do that? I couldn't have driven my GTR the way i did if it was only RWD.

 

hi

on the bulkhead it lists the engine supplied from factory as RB25DE....i assume the T means turbo so it prob started life as a N/A GTS4 before having a conversion

can anyone give me info on a replacement turbo for this car...im putting autronic on the car very soon and may as well change the turbo at that point....id much rather have a turbo that bolts straight up to the stock manifold and exhaust, bought too much custom stuff in the past to know that custom normally means "bad fit" lol

ive seen a kit on ebay that seems very cheap but the exhaust compressor looks very big and im sure they are a rip off?

whats the chances of just fitting a RB26 twin turbo manifold (seen a couple about) and it just bolting up?

regards, brian

 

High CR and lots of RPM is going to mean you DO need a huge hot side on the turbo mate, but i will leave it to those with direct experience to say exactly what obviously.

 

The ebay stuff has a huge exhaust housing as its a load of ripoff shite from a diesel truck.

Do NOT get ebay junk.

You dont need a huge hot side either, best results i seen was a good 650odd bhp and lots of torque using a GT35R with a .82 exhaust housing, ie the middle sized one.

RB26 manifold wont fit a RB25 head, and no reason to do that, RB26 twin turbo setup just means fuckloads of pipes and grief for nothing.

Ring up InvoAuto and speak to Tommy "FIA aprooooved, innit" Chung, im sure he does stainless single turbo RB25 manifolds for about 250quid that will enable you to fit a big single turbo and external gate of your choice.

If you wanna stick to standard manifold then its a T25 flange and biggest you can fit that i can think of is GT3071R-WG and thats good for 450bhp.

 

To brian a .82 will sound huge mate, its all relative and he is used to the calibra turbo, lol

 

cheers!

some good skyline info for once!

 

http://www.atpturbo.com/Merchant2/me...egory_Code=GRT

so if ive understood, this is the turbo that fits on with a flange change on the turbo side of the manifold and i expect some modding on the exhaust side of the turbo to get it to bolt up to that?

dont know much about turbo's TBH

 

Yea, that will fit to your manifold, but will no doubt have to modify the downpipe a bit.

The exhuast housing flange there is similar to the RB25 turbos one at first glance, but no doubt will need some mods to fit the exhaust.

Personally id rather bin the standard manifold and go for a big-ish single, at least most of them have conventional exhaust outlets (4bolt or v-band) on the turbo which makes it easier to mod a downpipe to fit the fucker.

My mate had a RB25'd R32GTST with a single TD06 25G on it, thats a 600bhp turbo, and a old fashioned bus of one too, and was totally lag free and lovely to be honest.
Used to run 1.5bar boost on standard 9.5:1 compression GTST bottomend too with no probs, just uprated fueling, cooling, and so on...

 

well im looking for a problem free install so if the GT3071R-WG will bolt straight up to the manifold and just need downpipe mod then that may be the way ill go

450bhp will keep me hapy im sure....at the moment this car had trouble keeping up with a civic vvti

stock injectors good for 450bhp with the fuel pressure upped a bit?

what fuel pressure should i see at idle? (std)

 

No idea about stock fuel pressure on GTSTs, but id run 550cc inj's, standard on GTRs are 440s, but smaller on GTSTs, not good enough for a sale 450bhp anyhow.

Dont forget, that turbo is 450bhp at full flow, high boost, probably more than youl be able to run, so 400bhp will be more like it i reckon.

 

i thought 6x 440cc would be ok...

so i guess the limi of the stock turbo is around 280-300bhp?

 

But thats standard GTR inj size, not GTST inj, they only 370cc, so only good for 370bhp at a push.

They also side feed on GTSTs, so not interchangable with GTR which uses normal top feed inj's

 

ah, i see

cheers

 

silly question here but are the stock GTST injectors red in colour?

im trying to work out if my injectors and loom are GT or GTST



i have had some serious fuelling issues with this car

 

It seems that the injectors i have are actually NA injectors.....

starting to get concerned that the engine is in fact a NA engine with a turbo bolted on the side now.......


i have done a little researcha and the only info i can find on compression shows the RB25DE and the RB25DET engine at the same compression....is this true? (8.8:1)

are the NA and the GTST pistons the same?

 

Is there not an engine number prefix that dictates which it is?

Like XE/LET on a vauxhall lump so you know which bottom end it is?

 

cant find one mate.......i suspect the worst TBH, i think its an NA version mate = fecked!

just ordered a big ass turbo too

 

Oooh, not good Good old jap imports eh
Would make sence bearing in mind GTS4s were n/a only on all but R32s.

BTW you wrong bout compression...

RB25DE's are 10:1 compression.

RB25DET's are almost as big 9.5:1 compression (but can take decent boost, but mates had 1.5bar from a big TD06 25G on pump fuel thru his on std internals).

RB26DETT's are 8.5:1/8.6:1 comp (depend who you ask )

 

Are the rods and crank the same between the N/A and turbo motors?

If so, wouldnt be the absolute end of the world to have to put a set of pistons in it?

 

Might be of interest...

http://www.skylinesaustralia.com/for...howtopic=33407

IIRC RB25DET crank and rods are almost identical in weight and strength to RB26DETT ones (ie bulletproof), but RB25DE's are different, even the block is i think, no oil squirters drilled.

Dont quote me on that, im not 100%, just remembering stuff ive been told over the years. (might say in that link above, ive never actually read it )

 

ill have to do a compression test and come back

i have a feeling this car is NA........either this car burns or the pistons will have to get done

 

Good link that Steve

 

yes thats why the car was ony running 0.4 bar eh

now it all makes sence

i suppose it cant get any worse from here on

 

is there a number on the bottom end somewhere?

 

ok this may also seem like a silly question but what shape are the NA pistons?....i know mine are flat as i can point a lazer down the bore and i know the turbo pistons are flat at the top

being optimistic i presume the N/A would be pyramid shape like some of the high comp XE engines iver worked on?

the other thing that points towards a turbo engine is that the turbo does not boost until over 2500rpm (cant remember exactly what rpm but its about 65-70mph in fifth)

regards, brian

 

just hope for the best brian!

 

and fear the worst.........


do that and you will NEVER be disapointed!

 

Cr doesnt make any difference to the boost threshold really, thats a myth.